Numerous chemical agents have conventionally been used to control plant diseases. However, the frequent use and over-administration of chemical agents having a similar structure and similar mode of action to control the same types of plant diseases has resulted in the significant problem of plant pathogens becoming resistant to these chemical agents.
On the other hand, there is currently a growing demand among consumers for agricultural products that are grown using reduced levels of agricultural chemicals as well as a social demand for a reduction in the burden that agricultural chemicals place on the environment.
In addition, in the case of treating agricultural crops by mixing two or more types of chemical agents by tank mixing at farm fields where chemical agents are actually used, the combining of incompatible chemical agents may cause a mutual reduction in the effects of the chemical agents or result in a considerable risk of causing phytotoxicity.
In consideration of such circumstances, there is a desire for a plant disease control composition that is highly effective against organisms that are resistant to existing chemical agents and exhibits higher efficacy using a smaller amount of active ingredient. Moreover, there is also a desire for a highly compatible plant disease control composition composed of components (compounds) having different basic structures and different modes of action and method for controlling plant disease in order to prevent plant pathogens from acquiring resistance.
A quinoline compound represented by general formula (I) is known to demonstrate control effects as a fungicide against rice blast (Pyricularia oryzae) and against gray mold (Botrytis cinerea) in tomatoes, cucumbers and green beans by treating plants by seed disinfection or foliage spraying and the like (Patent Documents 1 to 4), while the mixing of a quinoline compound represented by general formula (I) with a certain type of fungicide is disclosed in Patent Document 5.